Methods for preparing open-celled polyurethane foams, systems for use therein, and open-celled polyurethane foams produced thereby

ABSTRACT

Disclosed are methods and systems for preparing open-celled polyurethane foams by a discontinuous box foam process in which (a) a polyurethane foam-forming composition is deposited into a container having a gas-permeable base and (b) the polyurethane-foam forming composition is allowed to form an open-celled polyurethane foam in the container. In these methods and systems, the gas-permeable base is heated before, during, and/or after step (a) and heating is continued during at least a portion of step (b).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/733,116, filed Jun. 8, 2015, which is being incorporated by referenceherein.

FIELD

The present invention is directed to, among other things, methods andsystems for preparing open-celled polyurethane foams by a discontinuousbox foam process in which a polyurethane foam-forming composition isdeposited into a container and allowed to rise in the container to forman open-celled polyurethane foam.

BACKGROUND

Discontinuous box foam processes are used to produce water-blownopen-celled polyurethane foams used in many applications, such as, forexample, automotive hoodliners, headliners and sun shades. In thisprocess, a water-blown polyurethane foam-forming composition isdeposited, often by pouring, into a large box and allowed to rise andform an open-celled polyurethane foam, often referred to as a “bun”, inthe box. The exothermic polyurethane foam-forming reaction generatesheat. After the foam sets, a degas process takes place by suddenevaporation of a mixture of steam and CO₂, leaving a number of smallcraters on the surface of the slab. This blow-out process is the outwardsign that the foam cells have opened. After an additional 30 minutes orso, the bun is then typically removed from the box and allowed to coolat ambient conditions for roughly 24 to 48 hours. Once the foam bun hascooled, it is sliced to sheets of the desired thickness for the endproduct, such as an automotive hoodliner, headliner, and/or sun shades.Prior to such slicing, however, the sides and top and bottom of the bunare typically trimmed to square off the bun. This trimmed foam isgenerally waste.

One area of difficulty in such discontinuous box foam processes toproduce water-blown open-celled polyurethane foams is the degree ofwaste generated at the bottom of the bun. Water reacts with thepolyisocyanate in the composition during foam formation, which producescarbon dioxide. This carbon dioxide can generally escape from the upperportions of the open-celled polyurethane foam bun, but more oftenbecomes trapped in the bottom portion which creates large voids in thebottom portion of the bun following the degas process, resulting in afoam having a poor appearance and significantly lower density at thebottom of the bun relative to other portions of the bun. The portion ofthe bottom of the bun containing these large voids is waste.

Attempts have been made to minimize the waste produced from the bottomof the bun in such processes. For example, chemical modifications of thepolyurethane foam-forming composition, such as manipulation ofsurfactant and/or catalyst in the composition, have been attempted toincrease cell tightness. A problem with these compositional approaches,however, is that increasing cell tightness throughout the entire bun canhave a detrimental effect on physical properties of the resulting foamand also can detrimentally effect properties, such as acousticproperties, of the article, such as automotive hoodliner, headlinerand/or sun shade, produced from the foam.

As a result, it would be desirable to provide an improved discontinuousbox polyurethane foam process that reduces the amount of waste at thebottom portion of the polyurethane bun without making chemicalmodifications of the polyurethane foam-forming that could have adetrimental impact on the physical properties of the resultingopen-celled polyurethane foam bun or articles produced from such a foam.

SUMMARY OF THE INVENTION

In certain respects, the present invention is directed to methods forpreparing open-celled polyurethane foams. These methods comprise: (a)depositing a polyurethane foam-forming composition into a containerhaving a gas-permeable base; and (b) allowing the polyurethane-foamforming composition to form an open-celled polyurethane foam in thecontainer. In these methods, the gas-permeable base is heated before,during, and/or after step (a) and heating is continued during at least aportion of step (b), and the method is discontinuous.

In some respects, the present invention is directed to systems forpreparing open-celled polyurethane foams using the methods describedherein. These systems comprise: (a) a source of a polyurethanefoam-forming composition; (b) a container having a gas-permeable base;and (c) a heating device for the gas-permeable base of the container.

The present invention is also directed to, among other things,open-celled polyurethane foams produced by such methods and/or usingsuch systems.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of the container and heating deviceused to make open-celled foams in some of the Examples.

DETAILED DESCRIPTION

Various embodiments are described and illustrated in this specificationto provide an overall understanding of the structure, function,properties, and use of the disclosed inventions. It is understood thatthe various embodiments described and illustrated in this specificationare non-limiting and non-exhaustive. Thus, the invention is not limitedby the description of the various non-limiting and non-exhaustiveembodiments disclosed in this specification. The features andcharacteristics described in connection with various embodiments may becombined with the features and characteristics of other embodiments.Such modifications and variations are intended to be included within thescope of this specification. As such, the claims may be amended torecite any features or characteristics expressly or inherently describedin, or otherwise expressly or inherently supported by, thisspecification. Further, Applicant(s) reserve the right to amend theclaims to affirmatively disclaim features or characteristics that may bepresent in the prior art. Therefore, any such amendments comply with therequirements of 35 U.S.C. § 112 and 35 U.S.C. § 132(a). The variousembodiments disclosed and described in this specification can comprise,consist of, or consist essentially of the features and characteristicsas variously described herein.

Any patent, publication, or other disclosure material identified hereinis incorporated by reference into this specification in its entiretyunless otherwise indicated, but only to the extent that the incorporatedmaterial does not conflict with existing definitions, statements, orother disclosure material expressly set forth in this specification. Assuch, and to the extent necessary, the express disclosure as set forthin this specification supersedes any conflicting material incorporatedby reference herein. Any material, or portion thereof, that is said tobe incorporated by reference into this specification, but whichconflicts with existing definitions, statements, or other disclosurematerial set forth herein, is only incorporated to the extent that noconflict arises between that incorporated material and the existingdisclosure material. Applicant(s) reserves the right to amend thisspecification to expressly recite any subject matter, or portionthereof, incorporated by reference herein.

In this specification, other than where otherwise indicated, allnumerical parameters are to be understood as being prefaced and modifiedin all instances by the term “about”, in which the numerical parameterspossess the inherent variability characteristic of the underlyingmeasurement techniques used to determine the numerical value of theparameter. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter described in the present description should atleast be construed in light of the number of reported significant digitsand by applying ordinary rounding techniques.

Also, any numerical range recited in this specification is intended toinclude all sub-ranges of the same numerical precision subsumed withinthe recited range. For example, a range of “1.0 to 10.0” is intended toinclude all sub-ranges between (and including) the recited minimum valueof 1.0 and the recited maximum value of 10.0, that is, having a minimumvalue equal to or greater than 1.0 and a maximum value equal to or lessthan 10.0, such as, for example, 2.4 to 7.6. Any maximum numericallimitation recited in this specification is intended to include alllower numerical limitations subsumed therein and any minimum numericallimitation recited in this specification is intended to include allhigher numerical limitations subsumed therein. Accordingly, Applicant(s)reserves the right to amend this specification, including the claims, toexpressly recite any sub-range subsumed within the ranges expresslyrecited herein. All such ranges are intended to be inherently describedin this specification such that amending to expressly recite any suchsub-ranges would comply with the requirements of 35 U.S.C. § 112 and 35U.S.C. § 132(a).

The grammatical articles “one”, “a”, “an”, and “the”, as used in thisspecification, are intended to include “at least one” or “one or more”,unless otherwise indicated. Thus, the articles are used in thisspecification to refer to one or more than one (i.e., to “at least one”)of the grammatical objects of the article. By way of example, “acomponent” means one or more components, and thus, possibly, more thanone component is contemplated and may be employed or used in animplementation of the described embodiments. Further, the use of asingular noun includes the plural, and the use of a plural noun includesthe singular, unless the context of the usage requires otherwise.

As indicated, certain embodiments of the present invention are directedto methods for preparing open-celled polyurethane foams. The methods ofthe present invention are discontinuous. As used herein, the term“discontinuous” is synonymous with batch and refers to a method in whichthe container takes in all of the reactants of the polyurethanefoam-forming composition and then an open-celled foam is formed in thecontainer, and, during the period of this process, no reactants are fedinto or removed from the container. The discontinuous methods of thepresent invention are not a continuous method of foam production, inwhich a reaction mixture is applied to a moving film disposed on aconveyor belt and allowed to foam on the film.

As used herein, the term “open-celled polyurethane foam” refers to apolyurethane foam having an open-celled content of at least 60% byvolume, such as at least 75% by volume, such as 60 to 99% or 75 to 99%by volume, measured according to ASTM D6226—Open Cell Content byPycnometer. In certain embodiments, the open-celled polyurethane foamsproduced according to the present invention have a density of at least10 kg/m³, such as at least 15 kg/m³, or, in some cases, at least 20kg/m³ and/or up to 50 kg/m³, such as up to 45 kg/m³ or, in some cases,up to 35 kg/m³.

The methods of the present invention comprise depositing a polyurethanefoam-forming composition into a container having a gas-permeable base.As used herein, “container” refers to a receptacle for holding thepolyurethane foam-forming composition during the foaming process. Thecontainers used in the present invention may, in certain embodiments, bein the form of a box, which, as used herein, refers to a container,often in the form of a square or rectangle, that is formed by a base,such as a tray, and a plurality of side walls, such as at least 3 or atleast 4 side walls, and which may or may not have a cover or lid. Asindicated, in the present invention, the base of the container isgas-permeable, which means that the base, such as a tray, is disposedsuch that gas, such as air, can pass through the base to some extent andis constructed of a material through which gas, such as air, can pass tosome extent, examples of which include, but are not limited to, paper orcardboard, or a gas-permeable plastic film, such as a polymeric film,containing pinholes to make the film gas-permeable. The use of agas-permeable base is a critical feature of the present invention, sinceit is necessary that at least some gas in the bottom of the bun has ameans of escaping during the degas process used to produce theopen-celled polyurethane foams formed by the methods of the presentinvention. The base, in certain embodiments of the present invention,therefore, is not, for example, a plastic film. In certain embodiments,the container may be raised above a sub-surface, such as a floor, inorder to allow gas to flow through the base, such as where the containeris disposed on rails.

In certain embodiments, the polyurethane foam-forming composition isdeposited into the container by pouring, though other methods ofdepositing the composition into the container can be used if desired.

The polyurethane foam-forming compositions used in the present inventioncomprise a polyol component and a polyisocyanate component. Morespecifically, in certain embodiments of the methods of the presentinvention, open-celled polyurethane foams are obtained by reacting apolyisocyanate component with a polyol component which comprises: (a) apolyether polyol having a functionality of from 2 to 6 and a numberaverage molecular weight of more than 160 to 6500, such as where atleast 60% by weight, at least 80% by weight or, in some cases, at least90% by weight, based on total weight of polyol in the polyol component,is one or more such polyether polyol(s), (ii) a chain extending agentand/or crosslinking agent containing at least two isocyanate-reactivegroups and having a molecular weight of from 60 to 160, (iii) water, and(iv) a catalyst for polyurethane formation.

The polyisocyanate component used in the methods of the presentinvention may comprise one or more polyisocyanates, but, in certainembodiments, comprises diphenyl methane diisocyanate (mMDI), polyphenylpolymethylene polyisocyanate (pMDI) or a mixture of one or more diphenylmethane diisocyanates and one or more polyphenyl polymethylenepolyisocyanates. In certain embodiments, mixtures of a diphenyl methanediisocyanate and a polyphenyl polymethylene polyisocyanate in which from10 to 50% by weight of the total polyisocyanate is a diphenyl methanediisocyanate and from 50 to 90% of the total polyisocyanate is apolyphenyl polymethylene polyisocyanate, is used. In certainembodiments, 40 to 80% by weight, such as 45 to 75% by weight, of thetotal monomeric diphenyl methane diisocyanate isomers include 4,4′-,2,2′- and/or 2,4′-diphenyl methane diisocyanate.

As indicated, in certain embodiments, the polyol component comprises apolyether polyol having a functionality of from 2 to 6. In certainembodiments, the polyol component includes at least 60% by weight of apolyether polyol, such as at least 80% by weight, or, in some cases, atleast 90% by weight, of a difunctional, trifunctional or mixture of di-and tri-functional hydroxyl polyethers having an OH number of from 26 to1050 (these OH numbers correspond to a number average molecular weightof from more than 160 to 6,500 determined by the end group analysismethod).

In certain embodiments, the polyol component also comprises up to 40% byweight, such as up to 25% by weight, or, in some cases, up to 10% byweight, based on total weight of polyol, of other types of polymericpolyols such as polyester polyols and polymer filled polyols.

Examples of difunctional hydroxyl polyethers having an OH number of from26 to 1050 which may be used in the polyol component used in the methodsof the present invention include the difunctional polyethers obtained byreaction of ethylene oxide and/or propylene oxide with glycols such asethylene glycol, diethylene glycol, 1,2- or 1,3-propylene glycol,butane-1,4-diol, etc. Polypropylene oxides and/or polyethylene oxideshaving an OH number in this range, in some cases in the range of from147 to 560 (corresponding to a number average molecular weight of from200 to 763 as determined by the end group analysis technique) areexamples of suitable difunctional hydroxyl polyethers. These shortchained polyethers are, in certain embodiments, used in an amount offrom 15 to 35% by weight, based on the total weight of the polyolcomponent.

Trifunctional hydroxyl polyethers which may be employed in the polyolcomponent include the trifunctional polyethers obtainable by reaction ofethylene oxide or propylene oxide with trihydric alcohols, such asglycerol, trimethylol propane, monoethanolamine, triethanolamine,sucrose/propylene, glycol/water, etc. These polyethers often have an OHvalue of 26 to 1050 which corresponds to a number average molecularweight of from more than 160 to 6,500 as determined by the end groupanalysis method.

In certain embodiments, the polyol component comprises a mixture ofdifunctional and trifunctional hydroxyl polyethers. In certainembodiments, the polyol component comprises (i) 20 to 40% by weight,based on the total weight of the polyol component, of a polypropyleneoxide-based polyether diol, such as a glycerin-initiated polyether diol,having an OH number in the range of from 450 to 600, (ii) 30 to 50% byweight, based on the total weight of the polyol component of apoly(propylene/ethylene oxide) glycerin-initiated polyether triol havingan OH number in the range of from 26 to 34; and (iii) 10 to 30% byweight, based on the total weight of the polyol component, of apolypropylene oxide-based polyether triol, such as a glycerin-initiatedpolyether triol, having an OH number in the range of from 400 to 550,such as 445 to 495. Suitable polyethers polyols also includefiller-containing polyethers which contain approximately 20% by weightof a solid styrene/acrylonitrile copolymer grafted on or approximately20% by weight of a solid reaction product of toluene diisocyanate (TDI)and hydrazine in dispersed form.

As indicated, the polyol component included in the polyurethanefoam-forming compositions used in the methods of the present inventioncomprises a chain extending agent and/or crosslinking agent containingat least two isocyanate-reactive groups and having a molecular weight offrom 60 to 160, specific examples of which include, but are not limitedto, glycerol, butanediol, ethylene glycol, diethylene glycol, propyleneglycol, ethylenediamine, ethanolamine, triethanolamine,trimethylolpropane and pentaerythritol, including mixtures of two ormore thereof.

In certain embodiments, such a chain extending agent and/or crosslinkingagent is present in an amount of at least 1% by weight, such as at least5% by weight and/or up to 20% by weight or, in some cases, up to 10% byweight, based on the total weight of the polyol component.

In the methods of the present invention, the blowing agent used in thepolyurethane foam-forming composition comprises water. In addition towater, other blowing agents may also be used, such as, for example,hydrocarbons, hydrofluorocarbons, including, but not limited to, C₃ andC₄ polyfluoroalkanes and polyfluoroalkenes (including, but not limitedto, any isomers of 1-chloro-3,3,3-trifluoropropene and2-chloro-3,3,3-trifluoropropene), including hydrochlorofluorocarbons. Incertain embodiments, water is included in an amount of 1 to 9% byweight, such as 2.5 to 7% by weight, or, in some cases, 3 to 6% byweight, based on total weight of the polyol component. If any otherblowing agents are included, such other blowing agent are often not beemployed in an amount greater than 2% by weight. In certain embodiments,water is the sole blowing agent used in the polyurethane foam-formingcomposition.

In certain embodiments, the polyol component also comprises a foamstabilizer and/or a cell opener, such as where the polyol componentcomprises 0.01 to 2% by weight, such as 0.1 to 0.7% by weight, of a foamstabilizer and/or cell opener based on the total weight of the polyolcomponent. Any foam stabilizer and/or cell opener is suitable, such as,for example, silicone foam stabilizers, such as those having arelatively short polyether group and a relatively long silicone group.

In certain embodiments of the methods of the present invention, thepolyol component comprises a catalyst for polyurethane formation, suchas a modified amine catalyst, such as where the modified amine catalystis included in an amount of from 0.5 to 8% by weight, such as 1 to 5% byweight, or, in some cases, 2 to 4% by weight, based on total weight ofthe polyol component.

In certain embodiments of the present invention, the modified aminecatalyst comprises the reaction product of (1) an amine, such as anamine having at least two amino groups, with at least one of those aminogroups being a tertiary amino group with (2) an oil, such as a bio-basedoil or a derivative thereof having a molecular weight of 500 to 800. Incertain embodiments, the modified amine catalyst comprises a reactionproduct of (1) amines such as those represented by the formulaR₂—N—R′_(x)—NH₂ where R and R′ each represents a hydrocarbon and xrepresents an integer, such as N,N-dimethyl-propylene diamine with (2)an oil, such as castor oil or any fatty acid, such as tall oil. Incertain embodiments, the modified amine catalyst is a reaction productof N,N-dimethyl-propylene diamine with tall oil.

In addition to or, in some cases, in lieu of, the aforedescribedmodified amine catalyst, the polyol component may comprise other knowncatalyst(s) for polyurethane formation.

Other known auxiliaries and additives may also be used in the productionof foams in accordance with the process of the present invention.Examples of such optional additives include, for example, surface-activeadditives, such as emulsifiers; cell regulators, such as paraffins,fatty alcohols and dimethyl polysiloxanes; pigments or dyes;flameproofing agents such as trischloroethyl phosphate and tricresylphosphate; stabilizers against the effects of aging and weathering;plasticizers; fungistatic and bacteriostatic agents; and fillers, suchas barium sulfate.

In certain embodiments of the present invention, the polyol component ismixed with the polyisocyanate component in a ratio by weight of polyolto isocyanate of from 100:150 to 100:200. This mixing is often carriedout in a low-pressure or a bucket type foaming machine. In certainembodiments, the polyol component and the polyisocyanate component aremixed in a ratio such that the NCO/OH index is 75 to 130, such as 85 to125 or, in some cases, 100 to 120.

In the methods of the present invention, the polyurethane-foam formingcomposition is allowed to form an open-celled polyurethane foam in thecontainer. In certain embodiments, the foamable mixture is activated sothat the foaming reaction begins in 30 to 60 seconds, as measured fromthe emergence of the first amount of the foam-forming composition from amixing head (referred to as “cream time”). In certain embodiments, after150 to 200 seconds, as measured from the emergence of the first amountof the foam-forming composition from the mixing head, the foam gels(referred to as “gel time”) and, after 3 to 5 minutes, as measured fromthe emergence of the first amount of the foam-forming composition fromthe mixing head, the degas process occurs, i.e. the sudden evaporationof a mixture of steam and CO₂, leaving a number of small craters on thesurface of the slab. This blow-out process is the outward sign that thefoam cells have opened, thereby forming an open-celled polyurethanefoam.

It is a critical feature of the present invention that the gas-permeablebase of the container is heated before, during, and/or after step (a)and heating is continued during at least a portion of step (b). Incertain embodiments, the heating is continued during all of step (b).

In certain embodiments, the heating of the gas-permeable base isaccomplished by a heating device, such as a heating pad, matt or platedisposed beneath the gas-permeable base, though other devices forheating the base can be envisioned, such as, for example, heating thegas-permeable base in an oven or under an infrared lamp or other deviceprior to inclusion of the base as part of the container. In certainembodiments, the heating device is a pad, matt or plate that isdimensioned to have a length at least as long as the length of the baseof the container and a width at least as wide as the width of the baseof the container. In certain embodiments of the present invention, thebase is heated to a temperature of at least 25° C., such as at least 30°C., at least 35° C. or at least 40° C. and, in some cases, up to 120°C., such as up to 90° C., such as up to 70° C. or up to 65° C. or up to60° C. Moreover, in certain embodiments, the base is heated to atemperature of at least 10° C., such as at least 15° C. or, in somecases, at least 20° C. higher and, in some cases, no more than 50° C.,such as up to 30° C. higher than the temperature of the ambient air inwhich the container is disposed. As a result, in certain embodiments,the base is heated to a temperature of at least 10° C., such as at least15° C. or, in some cases, at least 20° C. higher and, in some cases, nomore than 50° C., such as up to 30° C. higher than the temperature ofthe other portions of the container, including the side walls of thecontainer and/or the cover or lid (if any). As indicated, in certainembodiments, such a temperature is continued during the entirety of step(b) of the methods of the present invention. In some embodiments of thepresent invention, such heating is continued, and the temperature of thebase is maintained within one or more of the above-recited ranges,during the entire period from the beginning of the emergence of thefirst amount of the foam-forming composition from a mixing head throughthe degas process.

It should be appreciated that the methods of the present invention alsocontemplate the optional heating of only a bottom portion of the sidewalls of the container, in addition to the base, provided, however,that, in certain embodiments, the entire surface of the side walls isnot heated at least to the same extent as the base. For example, incertain embodiments, up to 10% of the length of the side walls,proximate to the base, may also be heated in the same manner or adifferent manner as the base. In certain embodiments of the presentinvention, only the gas-permeable base of the container is heated asdescribed above.

In certain embodiments, the foams produced by the methods of the presentinvention are used for the production of automobile hoodliners,headliners and/or sun shades. The foams can have a glass transitiontemperature of about 150° C. and, hence, high heat resistance and canhave almost no resilience, so that edges which are tightly compressed todifferent extents retain their cross-section. This compression retentionensures an exact fit of the parts required during installation.

It has been discovered, surprisingly, that the discontinuous methods forpreparing open-celled polyurethane foams of the present invention canresult in the production of an open-celled polyurethane foam bun inwhich the amount of large voids in the bottom portion of the bun iseliminated or at least significantly reduced relative to the sameprocess in which the gas-permeable base of the container is not heated,thereby eliminating or at least significantly reducing the amount ofwaste produced from the bottom of the bun, without detrimentallyeffecting the physical properties of the foam or the acoustic propertiesof the articles produced using the foam. Without being bound by anytheory, it is believed that the foregoing results arise because themethods of the present invention produce a high molecular weightpolyurethane at the bottom portion of the bun more quickly than otherportions of the bun, thereby producing a foam bun with a higher foamdensity, and cell tightness, at the bottom portion of the bun relativeto other portions of the bun. This higher foam density, it is currentlybelieved, prevents steam and/or CO₂ produced during the foam-formationprocess from opening the foam cells at the bottom of the bun during thedegas process described above. As a result, the present invention isalso directed to the discontinuous methods for preparing open-celledpolyurethane foams of the present invention described above wherein themethod produces a foam bun having a higher foam density at one sidethereof (the side proximate to the base of the container), such wherethe higher density portion extends for a length of up to 10% of thetotal height of the bun, than the density of the remaining portion ofthe bun.

As will be appreciated from the foregoing description, other embodimentsof the present invention are directed to systems for preparingopen-celled polyurethane foams. These systems comprise: (a) a source ofa polyurethane foam-forming composition, such as the polyurethanefoam-forming compositions described above; (b) a container having agas-permeable base, such as those described above; and (c) a heatingdevice for the gas-permeable base of the container, such as thosedescribed above.

As will be appreciated by the foregoing, some embodiments of the presentinvention are directed to methods for preparing open-celled polyurethanefoams by the methods described herein, comprising: (a) depositing apolyurethane foam-forming composition into a container having agas-permeable base; and (b) allowing the polyurethane-foam formingcomposition to form an open-celled polyurethane foam in the container,wherein the gas-permeable base is heated before, during, and/or afterstep (a) and heating is continued during at least a portion of step (b)and wherein the method is discontinuous.

Some embodiments of the present invention are directed to a method ofthe previous paragraph, wherein the open-celled polyurethane foam has anopen-celled content of at least 60% by volume, such as at least 75% byvolume, such as 60 to 99% or 75 to 99% by volume, measured according toASTM D6226—Open Cell Content by Pycnometer.

In certain embodiments, the present invention is directed to a method ofeither of the previous two paragraphs, wherein the open-celledpolyurethane foam has a density of 10 to 50 kg/m³, such as 15 to 45kg/m³ or 20 kg/m³ to 35 kg/m³.

Certain embodiments of the present invention are directed to a method ofany of the previous three paragraphs, wherein the container is in theform of a box, which, in some embodiments, is in the form of a square orrectangle, that is formed by a base, such as a tray, and a plurality ofside walls, such as at least 3 or at least 4 side walls, and which mayor may not have a cover or lid.

In some embodiments, the present invention is directed to a method ofany of the previous four paragraphs, wherein the gas-permeable base isconstructed of paper or cardboard and, in some embodiments is not aplastic film and, in some embodiments, is raised above a sub-surface,such as a floor, such as where the container is disposed on rails.

Certain embodiments of the present invention are directed to a method ofany of the previous five paragraphs, wherein the polyurethanefoam-forming composition is deposited into the container by pouring.

In certain embodiments, the present invention is directed to a method ofany of the previous six paragraphs, wherein the open-celled polyurethanefoam is obtained by reacting a polyisocyanate component with a polyolcomponent which comprises: (i) a polyether polyol having a functionalityof from 2 to 6 and a number average molecular weight of more than 160 to6500, such as where at least 60% by weight, at least 80% by weight or,in some cases, at least 90% by weight, based on total weight of polyolin the polyol component, is one or more such polyether polyol(s), (ii) achain extending agent and/or crosslinking agent containing at least twoisocyanate-reactive groups and having a molecular weight of from 60 to160, (iii) water, and (iv) a catalyst for polyurethane formation, suchas where the polyisocyanate component comprises a mixture of a diphenylmethane diisocyanate and a polyphenyl polymethylene polyisocyanate inwhich from 10 to 50% by weight of the total polyisocyanate is a diphenylmethane diisocyanate and from 50 to 90% of the total polyisocyanate is apolyphenyl polymethylene polyisocyanate, is used, such as where 40 to80% by weight, such as 45 to 60% by weight, of the diphenyl methanediisocyanate is 2,4′-diphenyl methane diisocyanate; and/or wherein thepolyol component includes at least 60% by weight of a polyether polyol,such as at least 80% by weight, or, in some cases, at least 90% byweight, of a difunctional, trifunctional or mixture of di- andtri-functional hydroxyl polyethers having an OH number of from 26 to1050 and/or wherein the polyol component also comprises up to 40% byweight, such as up to 25% by weight, or, in some cases, up to 10% byweight, based on total weight of polyol, of other types of polymericpolyols such as polyester polyols; and/or the polyol component comprisesa mixture of difunctional and trifunctional hydroxyl polyethers, such aswhere the polyol component comprises (i) 20 to 40% by weight, based onthe total weight of the polyol component, of a polypropylene oxide-basedpolyether diol, such as a glycerin-initiated polyether diol, having anOH number in the range of from 450 to 600, (ii) 30 to 50% by weight,based on the total weight of the polyol component of apoly(propylene/ethylene oxide) glycerin-initiated polyether triol havingan OH number in the range of from 26 to 34; and (iii) 10 to 30% byweight, based on the total weight of the polyol component, of apolypropylene oxide-based polyether triol, such as a glycerin-initiatedpolyether triol, having an OH number in the range of from 400 to 550,such as 445 to 495; and/or the chain extending agent and/or crosslinkingagent contains at least two isocyanate-reactive groups and has amolecular weight of from 60 to 160, such as where such a chain extendingagent and/or crosslinking agent is present in an amount of at least 1%by weight, such as at least 5% by weight and/or up to 20% by weight or,in some cases, up to 10% by weight, based on the total weight of thepolyol component; and/or the catalyst comprises a modified aminecatalyst, such as where the modified amine catalyst is included in anamount of from 0.5 to 8% by weight, such as 1 to 5% by weight, or, insome cases, 2 to 4% by weight, based on total weight of the polyolcomponent, such as where the modified amine catalyst comprises thereaction product of (1) an amine, such as an amine having at least twoamino groups, with at least one of those amino groups being a tertiaryamino group with (2) an oil, such as a bio-based oil or a derivativethereof having a molecular weight of 500 to 800, such as a reactionproduct of (1) amines such as those represented by the formulaR₂—N—R′_(x)—NH₂ where R and R′ each represents a hydrocarbon and xrepresents an integer, such as N,N-dimethyl-propylene diamine with (2)an oil, such as castor oil or any fatty acid, such as tall oil, such asthe reaction product of N,N-dimethyl-propylene diamine with tall oil.

Certain embodiments of the present invention are directed to a method ofany of the previous seven paragraphs, wherein the polyol component ismixed with the polyisocyanate component in a ratio by weight of polyolto isocyanate of from 100:150 to 100:200 and/or the polyol component andthe polyisocyanate component are mixed in a ratio such that the NCO/OHindex is 75 to 130, such as 85 to 125 or, in some cases, 100 to 120.

In certain embodiments, the present invention is directed to a method ofany of the previous eight paragraphs, wherein the polyurethane-foamforming composition is allowed to form an open-celled polyurethane foamin the container, such as where the foamable mixture is activated sothat the foaming reaction begins in 30 to 60 seconds, as measured fromthe emergence of the first amount of the foam-forming composition from amixing head; after 150 to 200 seconds, as measured from the emergence ofthe first amount of the foam-forming composition from the mixing head,the foam gels; and/or after 3 to 5 minutes, as measured from theemergence of the first amount of the foam-forming composition from themixing head, the degas process occurs.

Some embodiments of the present invention are directed to a method ofany of the previous nine paragraphs, wherein the heating of thegas-permeable base is accomplished by a heating device, such as aheating pad, matt or plate disposed beneath the gas-permeable base, suchas a heating pad, matt or plate that is dimensioned to have a length atleast as long as the length of the base of the container and a width atleast as wide as the width of the base of the container.

In some embodiments, the present invention is directed to a method ofany of the previous ten paragraphs, wherein the base is heated to atemperature of at least 25° C., such as at least 30° C., at least 35° C.or at least 40° C. and, in some cases, up to 120° C., such as up to 90°C., such as up to 70° C., up to 65° C. or up to 60° C.; and/or the baseis heated to a temperature of at least 10° C., such as at least 15° C.or, in some cases, at least 20° C. higher and, in some cases, no morethan 50° C., such as up to 30° C., higher than the temperature of theambient air in which the container is disposed; and/or the base isheated to a temperature of at least 10° C., such as at least 15° C. or,in some cases, at least 20° C. higher and, in some cases, no more than50° C., such as up to 30° C., higher than the temperature of the otherportions of the container, including the side walls of the containerand/or the cover or lid (if any).

In certain embodiments, the present invention is directed to adiscontinuous method of any of the previous eleven paragraphs, whereinthe heating is continued during the entirety of step (b) of the method,such as where heating is continued, and the temperature of the base ismaintained within one or more of the ranges recited in the immediatelypreceding paragraph, during the entire period from the beginning of theemergence of the first amount of the foam-forming composition from amixing head through the degas process.

Some embodiments of the present invention are directed to a method ofany of the previous twelve paragraphs, wherein the method produces afoam bun having a higher foam density at one side thereof (the sideproximate to the base of the container), such where the higher densityportion extends for a length of up to 10% of the total height of thebun, than the density of the remaining portion of the bun.

As will also be appreciated by the foregoing, some embodiments of thepresent invention are directed to systems for preparing open-celledpolyurethane foams by any of the methods described herein that comprise:(a) a source of a polyurethane foam-forming composition, such as any ofthe polyurethane-foam forming composition described in any one of theprevious thirteen paragraphs; (b) a container having a gas-permeablebase, such as any container described in any of the previous thirteenparagraphs; and (c) a heating device for the gas-permeable base of thecontainer, such as any heating device described in any of the previousthirteen paragraphs.

The present invention is also directed to, among other things,open-celled polyurethane foams produced by any method and/or using anysystem described in any of the previous fourteen paragraphs.

The non-limiting and non-exhaustive examples that follow are intended tofurther describe various non-limiting and non-exhaustive embodimentswithout restricting the scope of the embodiments described in thisspecification.

EXAMPLES

The materials used in the Examples were as follows:

POLYOL A: A glycerin-initiated polyether polyol having a functionalityof 3 and a molecular weight of approximately 6000.

POLYOL B: A propylene glycol initiated polyether polyol having afunctionality of 2 and a molecular weight of 218.

POLYOL C: A glycerin-initiated polyether polyol having a functionalityof 3 and a molecular weight of 358.

CATALYST: A modified amine catalyst of the type described in U.S. PatentApplication Publication No. 2008/0227879 A1.

SURF: A silicone cell-opening surfactant

CROSS: A crosslinking agent

H₂O: Water, the blowing agent.

DR2205: Colormatch® DR2205 black pigment from Chromoflo Technologies.

ISO: A mixture of diphenyl methane diisocyanate and a polyphenylpolymethylene polyisocyanate in which from 10 to 50% by weight of thetotal polyisocyanate is a diphenyl methane diisocyanate and from 50 to90% of the total polyisocyanate is a polyphenyl polymethylenepolyisocyanate.

Example 1

The materials listed in Table 1 were combined in the amounts indicated.The polyols and additives were combined to form the polyol componentbefore being combined with the polyisocyanate component in a suitablecontainer. Both the polyol component and the polyisocyanate componentswere adjusted to a temperature of 24.5° C. to 25.5° C. The polyolcomponent was charged to the container first, and then thepolyisocyanate component was added. The resulting foam-formingcomposition was mixed with a high speed mixer at 2700 to 2900 rpm. Thetimer was started at the beginning of the mixing.

TABLE 1 Ingredient Amount (parts by weight) POLYOL A 39 POLYOL B 27.75POLYOL C 18 CROSS 7.6 CATALYST 2.75 H₂O 4.1 SURF 0.5 DR2205 0.5 ISO 165NCO/OH Index 113

Examples 2-4

After about 20 seconds of mixing, approximately 800 grams of thefoam-forming composition was poured into a 13.5″×13.5″×6.5″ wooden box10 of the type depicted in FIG. 1 that had a cardboard base 40. Forexamples 3 and 4, the box 10 was disposed on a heating plate 20, asshown in FIG. 1, whereas for Example 2 the box 10 was disposed on a woodsurface. For example 3, no heat was applied to the base 40 of thecardboard box 10, whereas, for example 4, heat was applied by theheating plate 20 so that the temperature of the base 40 of the cardboardbox 10 was 50° C. Temperature probes 30 were placed on the heating plate20, inside the box 10 on top of the cardboard base 40, and on a sidewall of the box 10, as illustrated in FIG. 1. The reactivity of thepolyurethane foaming forming composition, the resulting foam density,and the appearance of the bun bottom of the bun were evaluated. Resultsare set forth in Table 2.

TABLE 2 Cream Time¹ Gel Time² Degas time³ Bun Foam density Bun bottomExample (seconds) (seconds) (seconds) (kg/m³) appearance.⁴ 2 44 178 20234.43 Big voids throughout; the bottom 1.5″-2″ of the bun were unusable3 Not measured 177 200 35.28 Big voids throughout; the bottom 1.5″-2″ ofthe bun were unusable 4 Not measured 174 192 34.75 No or only smallvoids at the bottom of the bun; only 0.25″ of the bun was unusable ¹Theperiod of time from the beginning of mixing of the polyol component withthe polyisocyanate until the mixture started to overflow from the mixingcontainer. ²A wooden stick was inserted into the bun periodically (3″deep in left corner of bun). Gel time was recorded as the time it tookfrom the beginning of mixing of the polyol component with thepolyisocyanate component until the foam depressed with stick pressure.³The period of time from the beginning of mixing of the polyol componentwith the polyisocyanate component until the start of first poppingbubbles in the foam

This specification has been written with reference to variousnon-limiting and non-exhaustive embodiments. However, it will berecognized by persons having ordinary skill in the art that varioussubstitutions, modifications, or combinations of any of the disclosedembodiments (or portions thereof) may be made within the scope of thisspecification. Thus, it is contemplated and understood that thisspecification supports additional embodiments not expressly set forthherein. Such embodiments may be obtained, for example, by combining,modifying, or reorganizing any of the disclosed steps, components,elements, features, aspects, characteristics, limitations, and the like,of the various non-limiting embodiments described in this specification.In this manner, Applicant(s) reserve the right to amend the claimsduring prosecution to add features as variously described in thisspecification, and such amendments comply with the requirements of 35U.S.C. § 112, first paragraph, and 35 U.S.C. § 132(a).

What is claimed is:
 1. A method for preparing an open-celledpolyurethane foam, comprising: (a) depositing a polyurethanefoam-forming composition into a box comprising a gas-permeable base andat least 4 sidewalls; and (b) allowing the polyurethane-foam formingcomposition to form an open-celled polyurethane foam in the container,wherein during step (a) and during step (b) the temperature of thegas-permeable base is maintained at least 10° C. higher than thetemperature of other portions of the box, and wherein the method isdiscontinuous.
 2. The method of claim 1, wherein the temperature of thegas-permeable base is maintained at least 10° C. higher than thetemperature of other portions of the box during the entire period oftime from the emergence of the first amount of foam-forming compositionfrom a mixing head through a degas process.
 3. The method of claim 1,wherein the gas-permeable base is constructed of cardboard.
 4. Themethod of claim 1, wherein the temperature of the gas-permeable base ismaintained at least 10° C. higher than the temperature of other portionsof the box during step (b) by heating the base with a heating pad, mattor plate disposed beneath the base.
 5. The method of claim 4, whereinduring step (b) the temperature of the gas-permeable base is maintained10° C. to 50° C. higher than the temperature of other portions of thebox.
 6. The method of claim 5, wherein only the base of the container isheated.
 7. The method of claim 6, wherein the base is heated to atemperature of at least 30° C. and up to 120° C.
 8. The method of claim7, wherein the base is heated to a temperature of at least 35° C. and upto 65° C.
 9. The method of claim 5, wherein the base is heated to atemperature of at least 10° C. higher than the temperature of theambient air in which the container is disposed.
 10. The method of claim1, wherein the open-celled polyurethane foam is in the form of a bunhaving a foam density at one side of the bun that is higher than thedensity of the remaining portions of the bun.
 11. The method of claim 1,wherein the open-celled polyurethane foam is obtained by reacting apolyisocyanate component with a polyol component which comprises: (i) apolyether polyol having a functionality of from 2 to 6 and a numberaverage molecular weight of more than 160 to 6500; (ii) a chainextending agent and/or crosslinking agent containing at least twoisocyanate-reactive groups and having a molecular weight of from 60 to160, (iii) water, and (iv) a catalyst for polyurethane formation.